Method of deslagging molten metal

ABSTRACT

A method of deslagging molten metal in which a ladle containing molten metal and slag is positioned beneath an uptake tube through which slag flows by vacuum. The slag is deflected by a baffle from the uptake tube into a slag collector, and a stream of gas is introduced transverse to the slag passing through the uptake tube to deflect the slag away from the baffle.

United States Patent 11 1 1111 3,867,132 Perry Feb. 18, 1975 METHOD OF DESLAGGING MOLTEN 3,266,881 8/1966 Novack CI :11 65/130 METAL 3,408,224 10/1968 Ashburn et a1. 75/49 X 3,565,411 2/1971 Grossman et a1 75/49 X Inventor: Thomas y, Chagrin Falls, 3,567,206 3/1971 Heggstad C131. 266/38 Ohio 3,595,549 7/1971 Skiild 266/34 V X [73] Assignee: Republic Steel Corporation, FOREIGN PATENTS OR APPLICATIONS Cleveland, 01110 406,339 2/1934 618211 1311111111 266/37 1 Filedl June 251 1971 OTHER PUBLICATIONS [21] App]. No.: 156,961 lndustriell Teknik, 94 (1966), p. 382, Patent Profy- Related US. Application Data laxls' [62] l3)i6v3i)s2i0On9(6)f Ser. No. 841,026, July 11, 1969, Pat. No. Primary Examiner Dewayne Rutledge Assistant Examiner-Peter D. Rosenberg u s CL Attorney, Agent, 0! Firm-C00per, Dunham, Clark,

,266/37, Griffin & Moran [51] Int. Cl C21c 7/10, C2lb 3/04, C2lb 3/04 [58] Field of Search 65/124, 125, 324, 19; [57] ABSTRACT 266/34 V1 371 38; 75/241 301 491 6] A method of deslagging molten metal in which a ladle containing molten metal and slag is positioned be- References Cited neath an uptake tube through which slag flows by vac- UNITED STATES PATENTS uum. The slag is deflected by a baffle from the uptake 124,700 3/1872 Sellers 266/38 tube into a Slag Collector, and a Stream Of gas is intro- 916,314 3/1909 H111 65/324 X duced transverse to the slag passing through the up- 3,116,999 1/1964 Armbruster 75/49 take tube to deflect the slag away from the baffle. 3,136,834 6/1964 Lorenz 75/49 X 3,179,512 4/1965 0155011 75/49 X 1 Clalm 8 Drawmg Flgures l l 1 I 1 1 1 1 I I PMENTED FEB] 8 I975 SHEET .3 OF 3 T METHOD OF DESLAGGING MOLTEN METAL CROSS REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION The present invention relates to a process for vacuum treatment of molten metal, particularly steel, in order to remove the slag portion which forms at the surface of the molten metal after it is prepared in a conventional melting furnace.

It is known in the steel-making art to employ vacuum devices for removing the slag from molten steel, but such devices generally utilize a siphon apparatus wherein a vacuum source is employed to initiate the flow of liquid metal through a narrow siphon tube into a receptacle located at a level beneath the level of the ladle containing the molten steel. There are many inherent deficiencies with these prior art vacuum mechanisms. For example, if the uptake tube disengages from the slag the process may become aborted and there will be difficulty in restarting the flow of slag; the devices are too inefficient to transfer large amounts of molten material; when the slag is too viscous it may be difficult to transport it through a narrow siphon tube; slag may build up and eventually close off the flow; and both slag and molten steel may be drawn into the unit. Anotherdeficiency of known processes is the need to continually repair or replace the portion of the uptake tube which enters the slag layer.

Other past methods followed to remove slag are pouring the slag from the ladle, scraping the slag from the molten steel while it is still in the furnace, and allowing a natural flow of the slag through holes in a wall of the furnace. Deslagging the molten steel in the furnace is a long and tedious process, and, more importantly, if slag remains and is present during the subsequent degassing process, that process will be prolonged and the quality of the product will be adversely affected, depending upon the volume of slag present. Similarly, deslagging the steel by pouring it from the ladle requires that the ladle be tilted, resulting in a rapid loss of heat which makes further processing more difficult. Moreover, this method of slag removal cannot always be carried out to completion and the slag removed may contain trapped iron (up to percent or more). Natural flow is also unacceptable in that it does not ensure the removal of the necessary quantity of slag and adjustment is difficult due to the varying nature and depth of the slag in each batch of steel.

Therefore, it is desirable to provide a process which rapidly and efficiently removes the slag from molten metal, which is relatively low in cost, which has readily replaceable expendable parts, and which utilizes in part existing facilities in a mill.

SUMMARY OF THE INVENTION An object of the invention is to provide a process to remove the slag from molten metal. In particular, an object is to provide an inexpensive, rapid and efficient method for deslagging steel wherein existing steel mill equipment may be used in part, the mechanism may be easily maintained, and a high quality end product is produced. An object is to provide for the collection of substantially all the slag while preventing gaseous and finely divided solid matter from interfering with the performance of the vacuum source.

To these and other ends, the instant invention a ladle adapted to contain the molten metal, a chamber and an associated vacuum source adapted to create a vacuum environment to draw the slag from the molten metal, and an uptake tube associated with the chamber and the ladle to funnel the slag from the molten metal to the chamber. A baffle within the chamber opposite the exhaust end of the uptake tube is disposed to deflect the slag so that it does not enter the vacuum source and a slag box located beneath the baffle is disposed to receive the slag after it is deflected by the baffle. In accordance with the invention, a transverse stream of gas is introduced to deflect slag away from the baffle.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammetric view of a deslagging pro cess.

FIG. 2 is a side elevational view of representative deslagging apparatus.

FIG. 3 is a front elevational view 3-3 of FIG. 2.

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3.

FIG. 5 is an elevational view of the cascade slag trap taken along line 5-5 ofFIG. 2.

FIG. 6 is a partial side elevational view of an alternative form of uptake tube useful in carrying out the pres ent invention.

FIG. 7 is a partial sectional view of a modified form of uptake tube.

FIG. 8 is a partial sectional view of alternative apparatus.

taken along line DETAILED DESCREPTION Referring to FIG. 1, a ladle 20 filled with molten metal such as molten steel from a conventional melting furnace (not shown) is first applied to a ladle deslagger 6 for removal of the slag in the ladle. Following the slag removing operation the ladle is transported to a ladle degasser 7 in which the charge within the ladle is degassed. Both deslagging and degassing are accomplished through the use of a large capacity vacuum source 8 coupled individually to the ladle deslagger 6 and the degasser 7 by valves 8a and 8b respectively. The valves are under the control of a control mechanism 9 which determines which of the deslagger and degasser is coupled to the vacuum source. Thus the sin gle vacuum source 8 supplies the necessary vacuum for removing slag and degassing the charge in these two sequential operations performed on molten metal in order to refine it.

FIGS. 2 to 8 show the details of a ladle deslagger 6. In connectionwith the deslagging of molten steel, vacuum deslagging in accordance with the present invention is most advantageously performed in connection with molten steel prepared in a basic oxygen furnace. Although producing a steel melt in a basic oxygen furnace is not essential to the process, if the steel should be prepared in an electric furnace, for example, it would be possible merely to scrape the slag from the surface of the melt before further vacuum treatment, although this would be time-consuming The deslagger 6 includes a chamber 10 coupled to the large capacity vacuum source 8 of FIG. 1 by a conduit I2 (FIG. 5) so as to create a vacuum environment within the chamber. An uptake tube 14 is coupled at one end 14a to the chamber 10, and has a second end 14b adapted to contact molten slag 16 forming a layer near the surface of molten steel 18 contained within the ladle 20. In one form of the apparatus (FIGS. 2 7), within the chamber 10 is located a baffle 22 (FIG. 4) disposed such that molten slag 16 being funneled through the uptake tube 14 is deflected by the baffle 22 into a slag box 24 forming a part of the chamber 10 and located beneath the baffle 22. In the form shown in FIG. 8, the uptake tube 14 is flared at its lower end to form an end cap 15 hav ing substantially the same cross-sectional area as the ladle 20. The vacuum causes both the slag l6 and the molten steel 18 to rise within the uptake tube 14 until the slag is caused to flow into the chamber 10 and then into the slag box 24. A baffle 22 may also be used with this arrangement to protect the vacuum system. A cascade slag trap 26 is further provided between the chamber 10 and its associated vacuum source 8 to prevent any slag which does not fall into the slag box 24 from entering into and interfering with the operation of the vacuum source 8.

The chamber 10 is a generally cylindrical housing formed in three sections and fabricated from a rela tively heat-resistant and high-strength material, e.g., steel. Thus, the chamber 10 comprises an open-ended cylindrical wall portion 28, tapered outwardly toward its lower portion when disposed in an upright position so that slag entering the chamber 10 near its top will not stick to the walls of the chamber; a cover portion 30 of generally circular shape and concave in the direction of the interior of the chamber 10; and the slag box 24 which forms the lower end of the chamber 10. Cooperating annular flanges 28a and 30a, located on the peripheries of wall portion 28 and cover portion 30, respectively, provide a means for bolting together the wall portion 28 and the cover portion 30. Similarly, co operating annular flanges 24a and 2812, located on the peripheries of the slag box 24 and the wall portion 28, respectively, are arranged so that the slag box 24 may be readily and detachably secured to the wall portion 28 of the chamber 10 at its lower extermity (which will be described in more detail below). Vacuum from the vacuum source 8 is introduced into the chamber 10 by means of an annular pipe 32 which enters the chamber 10 near the upper extermity of the wall portion 28.

Diametrically opposite the pipe 32 which permits the vacuum to be introduced within the chamber 10 is an aperture 33 in the wall portion 28 communicating with the uptake tube 14. The uptake tube is employed to funnel slag 16 from the ladle to the chamber 10. The uptake tube may be formed in two sections, a short section 14a permanently secured to the chamber 10 and disposed about the aperture 33 in the wall portion 28, and a longer section 14b designed to penetrate into the molten slag 16 and which is readily removable from the short section 14a so that the apparatus may be easily relocated, or repaired. In addition, different lengths of the longersections may be used with various sizes of ladles. It should be noted that the uptake tube 14 is preferably substantially straight, as if the tube should be bent or goose-necked, the molten slag 16 passing at high speed through the tube will tend to rapidly disintegrate the wall of the tube at the point of curvature. Preferably also, the short section 14a of the uptake 14 flares outwardly toward the aperture 33 so that the velocity of the slag 16 passing through the uptake tube decreases and the baffle 22 erodes less rapidly.

The uptake tube 14 shown in FIGS. 2 and 4 is comprised of an inner wall 14d and an outer wall and is beveled outwardly at its lower end. The outer wall 140 is fabricated from a material capable of withstanding the high temperature of the molten material being funneled there-through, e.g., preferably steel tube, but may also be graphite, a ceramic material, or the like, and is permanent in nature. The inner wall portion 14d is fabricated from multiple layers of char-resistant paper and is adapted to be disposed within and secured to the outer wall 140 to insulate the uptake tube 14 and to prevent the uptake tube 14 from collapsing upon evacuation under high temperature. The inner wall is temporary in nature. In more detail, the char-resistant inner wall 14d comprises a performed lining fabricated from a spirally wound strip of thermally-insulating paper, e.g., Kraft paper, layers of paper interleaved with layers of asbestos, or other impregnated paper or paper-like material. The inner wall 14d is designed to have only a short life, i.e., about 5 minutes or a long enough period to funnel all the slag 16 from the ladle 20 of molten steel, and to be readily removable and replaceable. The inner wall 14d should be approximately /2 inch in thickness, which is adequate to withstand the flow of slag for the time necessary to funnel the slag 16 from the ladle 20 to the chamber 10. The inner wall is disposed within the outer wall 14c throughout the entire length of the outer wall 140 from end 14a to end 14b and is held in place only at its bottom end by re fractory cement or other suitable adhesive. An additional wall portion He may be disposed about and se cured to the outer wall portion 140 near the end portion 14b of the uptake tube 14 which penetrates the slag 16 contained within the ladle 20. This additional wall portion 142 may also be fabricated from multiple layers of thermally-insulating paper or other suitable material but need only cover the outer wall 140 for a distance from the end 14b of the uptake tube 14 sufficient to protect the tube against direct contact with the slag, i.e., about 12 to 14 inches, the usual depth of the slag 16. The inner wall 14d and the additional wall portion l4e may be fabricated in one piece, being connected at their lower ends by paper connecting piece 14]" which also serves the function of protecting the outer wall 14c from deterioration. If the inner wall 14d and the wall portion 14c are not constructed integrally, the lower portion of the outer wall 140 should be protected by a suitable adhesive or the like.

Alternatively, the long section 14b of the uptake tube 14 may terminate in a cylindrical cup 17 located at the lower end of the tube and adapted to be disposed within the molten slag 16, as shown in FIG. 7. The cup 17 may be fabricated from thermally insulating paper, e.g., of the type used for inner wall 14d, or additional wall portion 142 and is intended to be discarded after removing the slag from one ladle of molten metal. The purpose of the cup 17 is to provide a smoother (less turbulent) entrance of the slag 16 into the uptake tube 14.

Located near the end 14b of the uptake tube 14 which penetrates into the slag 16 is a probe 34 for determin proximity ofthe uptake tube 14 to the steel-slag interface. The probe 34 is coupled to an electrical source (not shown) and relies upon the difference in conductivity of the molten steel 18 and the slag 16 to signal when the probe, which is disposed approximately inch below the end 14b of the uptake tube 14, has contacted the molten steel 18. Thus a predetermined amount of the slag may be removed without removing any of the molten steel.

As the uptake tube 14 is preferably stationary relative to the chamber 10, and the deslagging apparatus desirably remains fixed in one position, it becomes necessary that the ladle 20 be transported and raised until the slag portion 16 contained within the ladle 20 contacts the end 14b of the uptake tube 14. An operator may easily position the ladle 20 by means of positioning arms 36 that movably support the ladle. The operator may manipulate the ladle 20 such that the up take tube 14 contacts the slag 16 uniformly about the surface of the molten liquid, i.e., such as a vacuum cleaner is moved about a floor being cleaned. in order to bring the molten slag 16 closer to the open upper end of the ladle 20, the ladle may be tilted before the vacuum is applied by means of the uptake tube 14. Depending upon the viscosity of the slag layer, movement of the ladle may not be necessary. It should be understood, however, that the deslagging apparatus may also be moved into contact with the ladle 20. It is ordinarily easier for the operator to position the ladle with respect to the deslagging apparatus as part of the ladle movement from the furnace in which the steel is prepared to the ladle degassing station, which is normally a part of the process for producing high quality steel.

Disposed within the chamber is the baffle 22, which is suspended from the cover portion 30 in a position directly opposite the aperture 33 communicating with the uptake tube 14. Thus the baffle 22 may deflect slag which has been rapidly funneled by the uptake tube 14 into the chamber 10 from a path which would permit the slag to enter the pipe 32, which is disposed diametrically opposite the aperture 33 and which connects the vacuum source 8 to the chamber. As the baf- He 22 is directly in the path of rapidly moving, high temperature slag, it is necessary to reinforce the baffle with a suitable member 38, e.g., a-removable steel member or refractory material, to lengthen the life of the baffle. Although the reinforcement member 38 is not necessary to the operation of the present invention, it is more economic to utilize a replaceable massive block on the baffle 22 than to make the baffle 22 massive itself. The baffle 22 should not be disposed too close to the aperture 13 as the rapidly moving slag will cause the baffle to disintegrate too quickly.

Another method of preventing the rapidly moving slag from striking the baffle 22 at too fast a rate, and

which is in accordance with present invention is illustrated in FIG. 6. A stream ofgas, e.g., inert nitrogen gas or air, may be introduced transversely to the flowing molten slag by means of a pipe 19 and a valve 21 connecting a source of inert gas or air or both (not shown) to the short section 14a of the uptake tube 14 at a point close to the aperture 33 of the chamber 10. The inert gas or air deflects the molten slag 16 from its path of travel to prevent the slag from impinging too vigorously against the baffle 22. The inert gas or air is preferably introduced into the pipe 19 at a pressure of about 20 p.s.1.g.

In a modified form of apparatus, the long section 14b of the uptake tube 14 terminates in a flared substantially cylindrical end cap 15, as shown in FIG. 8. The end cap of the modified embodiment is comprised of an outer wall 15a fabricated from the same material as the uptake tube 14 and an inner wall 15b fabricated from thermally insulating material, e.g., thermally insulating paper such as that used to form inner wall 14d or additional wall portion Me, or, preferably, a refractory material.

The end cap 15 has substantially the same cross sectional area as the ladle 20 and is just able to be disposed within the ladle. The end cap is partially immersed within the molten material. The pressure acting on the portion of the molten slag and metal outside the perimeter of the end cap 15 is counterbalanced by the weight of a vertical column of metal of unit crosssectional area and of a height the same as the difference in levels between the slag outside the end cap and the upper end of the uptake tube (designated d in FIG. 8) plus the pressure within the chamber 10. Both the slag 16 and molten metal 18 are allowed to rise within the uptake tube 14. By carefully controlling the vacuum level produced by the vacuum source 8, only the slag will be drawn off the top of the uptake tube 14 and will enter the chamber 10.

That is, the pressure difference between the chamber and the surface of the slag layer outside the end cap 15 is controlled (by regulation of the vacuum source 8) so that it is sufficient to support a column filling the uptake 14 of slag alone or molten metal and slag but not molten metal alone. In this way the pressure difference forces slag (floating at the top of molten metal) upwardly and outwardly through the uptake tube into the chamber until all slag within the end cap has been removed. At this point the uptake tube is filled with molten metal and a small amount of slag at the upper end. The vacuum may be controlled so that the pressure difference is not great enough to support any more molten metal in the uptake tube, and hence the movement of molten material out the uptake-tube ceases. In this way all the slag but no molten metal is forced out the uptake tube. The vacuum within the chamber may be varied during this operation so as to provide a rapid flow of slag initially (higher vacuum) followed by a slowing of slag flow (lower vacuum) toward the end of the operation to ensure that no molten metal is withdrawn into the chamber.

Preferably, the ladle 20 is raised relative to the uptake tube 14 as the molten, slag is removed. Theend cap 15 may be disengaged from the molten metal in the ladle 20 when any of the molten metal begins to flow into the chamber 10, thus breaking the vacuum and allowing the remaining molten metal in the uptake tube 1 1 to run back into the ladle 20. There is no necessity for the receptacle for the slag to be disposed at a level beneath that of the ladle 20. The present apparatus does not utilize the same principles as a vacuuminitiated siphon, since in the instant device the vacuum is continuously in operation.

The baffle 22 may also be used with this form to prevent slag being drawn into the pipe 32 in the event that the vacuum is initiated at too high a rate. Thus, it is desirable to maintain a baffle 22 within the chamber 10 regardless of which form of apparatus is employed in order to avoid interference with the vacuum system.

After the slag 16 has been deflected by the baffle 22 within or has flowed into the chamber 10, a large proportion of the slag is received within the slag box 24 comprising a part of the chamber 10 and located beneath the baffleZZ. The slag box 24 is adapted to be readily removed from the chamber 10 upon its being filled. To this end, a plurality of wing-nut-and-bolt mechanisms 40 are employed to secure the slag box 24 to the lower periphery of the wall portion 28 of the chamber 10 at the corresponding annular flanges 24a and 28b. The slag box 24 may be transported away from and into its position in the deslagging apparatus by a transfer crane 41, for example. As the slag box 24 is adapted to contain molten slag 16, it should be lined with refractory brick 42 or other suitable material, although by the time the slag 16 is received within the slag box 24, the slag has substantially decreased in temperature.

While the slag box 24 receives the great proportion of the slag 16 removed from the ladle 20, some of the slag, particularly gaseous and finely divided solid matter, may manage to elude the slag box 24 and find its way to the pipe 32 which connects the vacuum source 8 to the chamber it. To prevent this portion of the slag from subsequently entering into and interfering with the operation of the vacuum source 8, the cascade slag trap 26 is provided to collect this slag. The cascade slag trap 26 comprises a series of vertical pipes 42 and 44 having their lower end portions sealed with caps 46 and 48 designed to catch the portion of the slag which settles in the pipes. In operation (as best seen in FIGS), the gaseous and finely divided solid matter of the slag enters the pipe 32, which has a horizontal portion 320 leading to the cascade slag trap 26 and a downwardly directed open-ended vertical portion 32b disposed within the first vertical pipe 42 of the cascade slag trap. Substantially of the slag matter existing from the open end of the vertical portion 32b of the connecting pipe 32 settles on the cap 46 at the base of the vertical pipe 42. However, some of the slag matter may manage to rise within the pipe 42 and enter the second pipe 44 of the cascade slag trap 26 at the point of connection of the pipes 42 and 44 near their upper ends. Again substantially all the remaining slag matter will settle on the cap 48 at the bottom of the second pipe 44. Extending from the central region of the second pipe 44 is a horizontal pipe 50 which leads directly to the vacuum source 8 through a flexible connector 52 and a valve 54. The valve 54 corresponds to the valve 8a shown in FIG. 1. In this case, the valve 54 is manually controlled. Although a cascade slag trap 26 containing two vertical pipes 42 and 44 is illustrated, it should be understood that one pipe may be sufficient to settle a substantial portion of the slag matter. A plurality of pipes will increase the efficiency of the system while not hindering the maintaining of the vacuum. Thus a tortuous path is provided to collect the portion of the slag not received by the slag box 24 before it can enter into and interfere with the operation of the vacuum source 8.

The entire deslagging apparatus may be supported by a pair offlanges 60, 62 located on the wall portion 28 of the chamber 10 which rest upon a pair of horizontal high-strength l-beams 56, 58.

The vacuum source 8 is preferably of larger capacity than necessary for adequately deslagging the molten steel 18. If the vacuum source 8 is of sufficiently large capacity, it may be used to provide a vacuum environment for the ladle vacuum degassing system. Common controls may also be utilized to determine the application of vacuum, as shown and described above in connection with FIG. 1. Thus both the slag portion 16 and the gaseous matter contained within the molten steel may be removed from the steel while the steel remains within the ladle 20. It is further desirable that the vacuum source 8 be of greater than adequate capacity so that a high vacuum may be placed in communication with the chamber 10 when such is desired, rather than having to reduce the pressure gradually. It should be noted that when a probe 34 is employed, a thin layer of slag will remain upon completion of the deslagging process; this is desirable as it provides temporary protection of the molten steel 18 during the time that the ladle 20 is being moved from the deslagging station to the degassing station.

The apparatus shown in FIGS. 2 7 allows for intermittent'operation near the end of the deslagging cycle, which is helpful in removing the slag 16. As the end point of slag removal is reached, the coupling together of slag and uptake tube is discontinued to prevent sucking molten steel into the chamber 10. The lost remnants of slag are then sucked into the chamber with intermittent coupling of uptake tube and slag. Such intermittent operation is not possible with the alternative arrangement, since once the tube and slag are decoupled no more sucking can take place.

Thus, the present invention provides a process for de slagging molten steel by removing the slag from the ladle by means of a high vacuum and utilizes a transverse stream of gas to prevent slag from impinging upon a baffle at too fast a rate.

I claim:

1. A method of deslagging molten metal, comprising;

a. locating a ladle means containing molten metal and a layer of slag beneath uptake tube means coupled to a chamber means including a vacuum source such that said uptake tube means is disposed substantially entirely about the upper surface of said slag and molten metal and is substantially immersed within said slag and molten metal; and

b. applying a vacuum to the slag and the molten metal contained in said ladle means through said uptake tube means to cause substantially all of said slag and a portion of said molten-metal to rise in said uptake tube means to transfer said slag to said chamber means, the pressure difference between said chamber means and the surface of said slag outside said uptake tube means being sufficient to support a column filling said uptake tube means of slag or slag and molten metal but not molten metal alone.

" UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent; 3,867,132 Dated 18 February 1975 q Inventor(s) Thomas E. Perry It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' Column 8, substitute the following claim for main claim 1 in the patent:

--l. A method of deslagging molten metal, comprising the steps of:

d (a) locating a ladle means containing molten metal and slag beneath uptake tube means associated with a chamber and a vacuum sourcesuch that said uptake tube means is disposed to contact the slag portion of said molten metal;

(b) applying a vacuum through the uptake tube means to the slag on the upper surface of said molten metal contained in said ladle means to remove a predetermined amount of said slag portion;

' (c) funneling said slag portion through said uptake tube means by said vacuum until said slag portion is deflected by baffle means within said chamber;

(d) introducing a stream of gas transversely to said slag portion funneled through said uptake tube .i means to deflect the slag away from said baffle means; and

(e) receiving said slag portion deflected by said baffle means in a slag collector beneath said baffle means.--

Signed and Scaled this fourth Day Of November 1975 [SEAL] Arrest:

RUTH C. MA SON C. MARSHALL DANN Altesrmg ()fflcer Commissioner oj'lalents and Trademarks 

1. A METHOD OF DESLAGGING MOLTEN METAL, COMPRISING; A. LOCATING A LADLE MEANS CONTAINING MOLTEN METAL AND A LAYER OF SLAG BENEATH UPTAKE TUBE MEANS COUPLED TO A CHAMBER MEANS INCLUDING A VACUUM SOURCE SUCH THAT SAID UPTAKE TUBE MEANS IN DISPOSED SUBSTANTIALLY ENTIRELY ABOUT THE UPPER SURFACE OF SAID SLAG AND MOLTEN METAL AND IS SUBSTANTIALLY IMMERSED WITHIN SAID SLAG AND MOLTEN METAL; AND B. APPLYING A VACUUM TO THE SLAG AND THE MOLTEN METAL CONTAINED IN SAID LADLE MEANS THROUGH SAID UPTAKE TUBE MEANS TO CAUSE SUBSTANTIALLY ALL OF SAID UPTAKE TUBE MEANS TO OF SAID MOLTEN METAL TO RISE IN SAID UPTAKE TUBE MEANS TO TRANSFER SAID SLAG TO SAID CHAMBER MEANS, THE PRESSURE DIFFERENCE BETWEEN SAID CHAMBER MEANS AND THE SURFACE OF SAID SLAG OUTSIDE SAID UNTAKE TUBE MEANS BEING SUFFICIENT TO SUPPORT A COLUMN FILLING SAID UPTAKE TUBE MEANS OF SLAG OR SLAG AND MOLTEN METAL BUT NOT MOLTEN METAL ALONE. 